High voltage/high current air break switches typically include an elongated conductive contact or “blade” that is locked or otherwise secured to a distal electrical terminal during operation to ensure that the components remain in contact. Relatively large forces must be established and overcome to move the blade into a locking position to assure a stable conductive connection.
Some previous designs provided blades that could be closed by exerting relatively low forces. In some of these designs, rotating an operating mechanism (e.g., and elongated shaft extending to the ground) would first cause the blade to pivot and enter the distal electrical terminal. Continued rotation of the operating mechanism would then pivot the blade about its longitudinal axis and into contact with the electrical terminal to establish the electrical connection.
These low-closing force switches are not without drawbacks, however. In particular, the blades of previous low-closing force switches are capable of pivoting about their longitudinal axis prematurely. There are two common ways in which this can occur. First, and when opening the switch, if the blade is rotated quickly and stopped suddenly, the momentum of the blade will overcome the force applied by springs to hold the blade in its open contact position (i.e., its rotational orientation about its longitudinal axis in which it does not contact the electrical terminal) and cause the blade to pivot about its longitudinal axis and stop in the closed contact position. Second, and when closing the switch, the blade may initially bounce off the distal electrical terminal and allow the blade to rotate about its longitudinal axis before it is properly seated in the electrical terminal. In both of these cases the switch cannot be subsequently closed using the operating mechanism.
Therefore, a need exists for an improved air break switch that addresses one or more of the above drawbacks of previous switch designs.